Age-related macular degeneration (AMD) is a significant health problem that affects millions of individuals and is the most common cause of severe vision loss among individuals over age 50 in the U.S. (Rein et al. 2006). The influence of genetic variation on AMD is strong and through the application of recent technological advances the genetic etiology of risk for AMD is being deconstructed. Independent studies, including our own, have identified and confirmed variations in multiple genes that affect risk to AMD, including CFH, HTRA1/ARMS2, C2/CFB, and C3 (DeAngelis et al. 2007;Edwards et al. 2005;Haines et al. 2005;Jakobsdottir et al. 2005;Klein et al. 2005;Maller et al. 2006;Rivera et al. 2005;Schaumberg et al. 2007;Schmidt et al. 2006;Hageman et al. 2005;Yates et al. 2007;Maller et al. 2007). Variation in these genes explain a significant portion of the genetic risk for AMD and ongoing studies are continuing to identify additional such genes. Also important are environmental risk factors such as smoking, hormone therapy and diet that contribute to AMD risk both independently and through their interactions with genes (Schmidt et al. 2006;Schaumberg et al. 2007;Wang et al. 2009). Again, ongoing studies are teasing apart these contributions. However, risk is just one of the many facets of the overall genetic architecture of AMD. Disease progression and treatment response are two critical elements also influenced by genetic variation (Shuler, Jr. et al. 2007;Seddon et al. 2007;Francis et al. 2009). The goal of this proposal is to increase our understanding of the genetic etiology of progression and treatment response in AMD, both of which have been understudied. Identifying the genes underlying clinical outcomes is directly relevant to better directing current treatments and developing new and better treatments and regimens for those suffering this disabling disorder.